After weeks of speculation, Nashville star Hayden Panettiere has revealed the news we have all been waiting for: she and fiancé Wladimir Klitschko are expecting their first child.

The American actress, who turned 25 on Thursday, confirmed the exciting announcement during her ALS ice bucket challenge.

Before being drenched with a bucket of ice cold water by US dancer and choreographer Derek Hough, Hayden nominated her fiancé Wladimir, 38, to complete the charity challenge, as well as American country music singer Kacey Musgraves. She then went on to add "and my unborn child", confirming all recent pregnancy rumours.

Derek, who previously dated Cheryl Fernandez-Versini, then posted the video along with Hayden's joyous news to his own Instagram page: "Couldn't figure out how to post it on @haydenpanettier 's twitter so I'm posting it for her . #als #icebucketchallenge (Hayden shortly went into labor after this ) Jus kiddin" he joked.

Hayden joins a host of other stars to complete the ice bucket challenge to raise funds for the research and treatment of motor neurone disease, such as Ben Affleck, David Beckham and Cara Delevingne.